Percussion drill bit for shattering hard formations



Oct. 1, 1968 M. BELEY 3,403 4 PERCUSSION DRILL BIT FOR SHATTERING HARD FORMATIONS Filed Feb. 21, 1967 INVENTOR. MCHAEL BELEY.

p M M ATTO R NEYS United States Patent 3,403,443 PERCUSSION DRILL BIT FOR SHATTERING HARD FORMATIONS Michael Beley, Pittsburgh, Pa., assignor to Dravo Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 21, 1967, Ser. No. 617,638 4 Claims. (Cl. 30-168) ABSTRACT OF THE DISCLOSURE A percussion bit is disclosed for breaking hard refractory and rock-like materials having wedges attached to the shank above and in separate planes from the customary cutting edge for applying a shattering impact against the material into which the bit is being driven.

This invention is for a drill bit for use in pneumatic or other power operating devices, or which may be used with a hand hammer, for breaking out refractory, cement and other formations of a hard, shatterable nature.

In knocking out the plug at the base of a blast furnace a chisel-like percussion type of rock drill is carried in a pneumatic drill operating unit at the front of a crawler. The crawler is brought to position at the base of the furnace and the drill operated to open the tap-hole. In this operation, it is desirable to break out the hard refractory plug rather than to merely drill a hole through it. This is typical of only one of many operations where breaking out or shattering a body of material is desirable, whereas percussion type tool bits are generally designed only to bore a hole and considerable maneuvering of the tool is necessary to accomplish the breaking out or shattering of a mass.

The present invention provides a tool bit which will more efietcively effect breaking or shattering a refractory, concrete or even rock mass which is to be broken out. To this end the tool comprises a conventional bit having a shank or drill stem with the customary straight chisel cutting end. However, with the present invention wedge-like wings are carried on the drill stem, spaced upwardly from the cutting end so that a lead hole will first be bored, followed at some short distance by the wedging impact of wings or fins. There are preferably a minimum of three such wings equally spaced from each other with none of them in the flat plane of the chisel. There may, however, be more, especially on larger size bits, and in such case some may be in the plane of the fiat sides of the bit.

The invention may be more fully understood by reference to the accompanying drawings, wherein:

FIG. 1 is a side elevation of a tool embodying my invention; and

FIG. 2 is a transverse section through the drill shank showing the top or trailing edges of the wings.

In the drawings 2 designates a drill stem or shank of generally circular section, but which of course may be polygonal. The upper end of the bit is of usual or conventional shape and has not been shown since it is unimportant to this invention. Its working end is flattened for a short distance, perhaps around one to three inches, back 3,403,443 Patented Oct. 1, 1968 from the cutting edge as indicated at 3, and this flattened portion terminates in a chisel-like cutting edge 4. This is a construction now well known and used in the industry.

According to the present invention a plurality of wedgelike wings 5 are carried on the shank back of the working end 3. These wings may be welded to the shank, preferably at equal distances from one another, and where there are but three, they are desirably all in planes which intersect the plane of the flattened working end. As here shown, they are in the approximate form to provide an effective right triangular shape with approximately equal sides, one side edge welded to the shank, one side edge 6 extending radially from the shank at the top and at right angles to the axis of the shank, and the hypotenuse 7 sloping from the outer top edge inwardly to the shank. The top edges of the wings define a circle of revolution, the diameter of which is greater than that defined by the cutting edge 4 when the tool is rotated about the axis of the shank, the maximum radius from the axis of the shank to the outermost corner of each wing desirably being greater than the total width of the cutting edge 3.

An equal-sided right triangular shape defines a relatively steep-sided inverted cone of revolution, since each hypotenuse or edge 7 is at a relatively obtuse angle of 45 to the axis of the tool, but the exact shape may be modified substantially, it being important only that the wings provide relatively obtuse wedge portions extending outwardly beyond the working dimension of the cutting end.

Since the wings are spaced back of the cutting end, the bit will cut a lead opening ahead of the wedges, and with a minimum of three equally-spaced wings, the tool will keep centered in the lead opening. By having the wings in planes that intersect the plane of the flat end portion 3, the wings do not simply act as an extension of the cutting edge.

When the tool is used, it is of course driven by successive blows into the formation. As the wedges follow the working end into the lead opening, they crack, break and shatter the frangible formation such as refractory material for which the tool is especially designed to be used. It will of course function in the same manner in other frangible hard bodies.

While I have shown and described one embodiment of my invention, it will be understood that various changes and modifications may be made therein within the contemplation of this invention.

I claim:

1. A drill bit for breaking frangible hard formations into which it is driven comprising a drill shank terminating in a flattened chisel-like working portion at one end with a cutting edge along the extreme end of the working portion, and a plurality of wedge-shaped wings on the shank above the chisel-like working portion and equidistantly spaced about the shank with at least two of the wings being in vertical planes that intersect the vertical plane of the flat chisel-like portion, the wings defining an inverted cone of revolution, the base diameter of which is greater than a circle of revolution of the cutting edge if the bit were rotated about its axis.

2. A drill bit as defined in claim 1 wherein the cone of revolution of the wings is at an angle of about 45 to the axis of the shank.

3. A drill bit as defined in claim 1 in which the wings References Cited are equally spaced about the shank, with a minimum of UNITED STATES PATENTS three wings, each of which is in effect triangular in shape with the hypotenuse extending upwardly and outwardly l 552 et a] gg:;gg from the shank and one edge extending along the shank 5 1784012 12/1930 Jowet; X and being fixed thereto.

4. A drill bit as defined in claim 3 in which the wings FOREIGN PATENTS are spaced back from the cutting edge a distance suflicient 1,325,064 3/1963 France.

to form a lead opening of at least an inch and said wings are in planes that intersect the plane of said flattened 10 ROBERT RIORDONPTI'MU Examine"- working portion. R. V. PARKER, JR., Assistant Examiner. 

